Catalytic condensation of hydrocarbons



Patented Au 27, 1940 PATENT OFFICE CATALYTIC CONDENSATION OFHYDROCARBONS Roderick D. Pinkerton, Chicago, IlL, and William Mendius,Munster, Ind., assignors to Sinclair Refining Company, New York, N. Y.,a corporation of Maine No Drawlng. Application February 18, 1939,

. Serial No. 257,102

'11 Claims. (01. 196-10)- This invention relates to improvements in thecatalytic condensation of low boiling hydrocarbons to produce normallyliquid hydrocarbons of gasoline boiling range.

The low boiling hydrocarbons to which we refer more particularly arethose saturated, or'

paraiiln, and unsaturated, or -olefin, hydrocarbons containing five andless carbon atoms per molecule, methane, ethane, ethylene, propane,

propylene, normal butane, isobutane, normal butylene, isobutylene,pentanes and pentenes.v

These hydrocarbons may be designated the C1,

Cr, C3, C4, and C5 compounds, or collectivelythe 05- compounds. 'Ofthese low boiling hydrocarbons the C1, C2, C3 and C4 compounds, orcollectively the C4 compounds, are normally gaseous hydrocarbons,whereas the C5 compounds are normally liquid hydrocarbons. Thehigherboiling hydrocarbons to which we refer are those containing six or morecarbon atoms per molecule within the boiling range of gasoline and maybe designated the Cs+ compounds.

The term catalytic condensation as applied to such hydrocarbons includespolymerization of unsaturates and alkylation or reaction betweensaturates and unsaturates. Catalytic polymerization of unsaturates hasbeen proposed, and practiced, as a method of recovering motor fuelgasoline of special value from less valuable hydrocarbon gas mixturescontaining suflicient unsaturated components. Gas mixtures so processedhave included gas mixtures from cracking operations containing asproduced sufllcient unsaturated components and gas mixtures pre-.Liminarily processed, catalytically or thermally, to produce suflicientunsaturated components by decomposition of saturated components. Whilesome of these previous proposals and practices the process of ourinvention effects catalytic,

condensation of mixtures of low boiling hydrocarbons including saturatesand unsaturates to pressure. As previously noted, alkylation reproducegasoline-like hydrocarbon products, superior in important respects tothose of polymerization processes, in which alkylation if occurring atall is merely incidental, with several important process advantages. 1 5In carrying out the process of our invention, we use a charging stockwhich comprises a mixture of low boiling hydrocarbons consistingpredominantly of C4- hydrocarbons and containing a substantial portionof C5 hydrocarbons, the 10 C4- hydrocarbons containing not less thanabout 40 mol percent. of ethane, propane and butanes, advantageously'notless than about l5,'of better 1 20, mol percent. of ethane and propaneand not more than about 25, 'or better 22, mol percent. 15 of normalbutylene and isobutylene on its total content of C4 hydrocarbons. The C5hydrocarhens in the charging stock comprise pentanes and. ntenes andshould be present in the mixture in an amount not less than about mol sopercent. on the totalcontent of C5 hydrocarbons. We pass this charging,stock in' contact with a phosphoric 'acid catalyst at a temperature ofabout 200-450 FL, or better about 200 to 360 F., under a pressureupwards of about 500 lbs. per square inch, or better upwards of about700 lbs. per square inch, whereby-we eflect substantial condensation ofsaturates and unsaturates, that is we effect substantial con densatlonby alkylation. The ethylene, propylene lyst, correlation of chargingstock composition, 40 7 temperature and pressure are important, but of'these three factors correlation of charging stock composition andtemperature appear to be more important, or at least more critical, thanthe 5 actions and polymerization reactions are inconsistent in somerespects. In particular, olefins may react either with olefins or withparatfins, whereas the paraflins react only with ole- 5 fins.Consequently, with a charging stock 01' given composition, olefinsbecome-less available for reaction with paraflins to the extent thatthey react with each other. In-carrying out our process, polymerizationis suppressed at least sub- to, polymerization as their molecular sizeincreases at least within the range of normally gaseous hydrocarbons. Wehave also found that lower temperatures tend to promote alkylation andsuppress polymerization whereas higher temperatures, at least within therange in which alkylation might otherwise be effected, tend to promotepolymerization and to suppress alkylation. In our process thecomposition of the charging stock and the temperature of catalystcontact are further interrelated in that, with any given temperature,alkylation can also be promoted by lowering the concentration of olefinsin the gas mixture, by lowering the concentration of olefins morereactive with respect to polymerization in the low boiling hydrocarbon'drocarbons of gasoline boiling range.

mixture or by increasing the concentration of paraillns more reactivewith respect to alkylation in the gas mixture. We have now discoveredthat the presence of C5 hydrocarbons increases the conversion of the C4-paraiilns with a resulting increase in the yield of condensed hy- Theuse of a charging stock containing a substantial proportion of C5hydrocarbons is of further advantage in that the alkylation of such acharging stock utilizes those C5 hydrocarbons which heretofore have notbeen amenable to recovery in the production of gasoline. The presence ofCu hydrocarbons in a charging stock subjected to the usualpolymerization processes is highly undesirable because these Cahydrocarbons are a source of overpolymerization with the result that the'end point of the polymerized product is too high and the life of thecatalyst is materially shortened. By using a substantial amount of C5hydrocarbons in a charging stock for our alkylation process the C5hydrocarbons are materially condensed into a useful product and not onlyincrease the yield from the C4- hydrocarbons but also improve thephysical characteristics of the resulting gasoline-like condensation ashereinafter more fully described.

In the process of our invention, these several factors are correlated asfollows: The temperature of catalyst contact is limited to a rangewithin which substantial alkylation can be effected. I At temperaturesabove about 330 to 360 F. consumption of oieflns in polymerizationbegins tointerfere with the alkylation reaction particularly if the gasmixture includes a substantial content of olefins more reactive withrespect to polymerization. Temperatures product above about 450 F. donot appear to be useful if substantial alkylation is to be effected. Attemperatures below about 200 F., difiiculties are encountered withrespect to control of moisture content of the catalyst, softening of thecatalyst and the stripping of condensation products from the catalyst.The composition of the charging stock is controlled, with respect to thetemperature of catalyst contact and the pressure, to promote alkylationand to limit polymerization impeding eflective alkylation. The chargingstock composition is controlled to include a substantial proportion butnot more than about; 25 mol percent. of C5 hydrocarbons on its totalcontent of C5-- hydrocarbons. The charging stock composition is alsocontrolledto include not less'than about 40 mol percent. of ethane,propane and butanes on its total content of C4- hydrocarbons and, withadvantage, to contain not less than about 15, or 20, mol percent. ofparaflins more reactive with respect to alkylation, ethane and propane,on its total content of C4- hydrocarbons, and with advantage not lessthan about 2 mol percent. of ethane, particularly reactive with respectto alkylation, on its total content of C4 hydrocarbons. The

charging stock composition is controlled to include a substantialproportion but not more than about 22 or 25 mol percent. of olefins morereactive with respect to polymerization, the butyltal content of C4hydrocarbons. Pressures up-- .wards of 500 lbs. per square inch areuseful in our process. In this range, somewhat higher pressures appearto be more useful than the 'lower pressures. Such higher pressures, up-

wards of about 700 lbs. per square inch for example, may assist insuppressing polymerization and promoting alkylation.

The period of catalyst contact is not critical. It must bev suflicientto effect the desired reactions, but it appears to have little if anypart in the distribution of olefin consumption between polymerizationreactions and alkylation reactions. Prolonged periods of catalystcontact may involve some alkylation of condensation products originallyproduced by polymerization. Within the region of catalyst contact, thehydrocarbons present may exist in liquid phase, in vapor phase or in amixture of liquid and vapor phases. The relatively low tempertures andthe relatively high pressures used in our process tend towards themaintenance of at least some liquid material within the region ofcatalyst contact, and some incidental advantages flow from thiscircumstance to the extenit that such liquid phase conditions exist.

We use the known phosphoric acid condensation catalysts in carrying outour process. An appropriate phosphoric acid catalyst may be prepared,for example, by mixing orthophosof the carrier, for example. Thecalcined.- mixture may be ground and sized or pelleted or somecarbonaceous material may be incorporated into themixture prior tocalcinatlon to render the calcination product porous.

Special apparatus for carrying out the proces of our invention is notnecessary. The catalyst contact chamber may be of any conventionaldesign appropriate to effect thorough contact between'the catalystarranged within the chamber and the charge passed therethrough and maybe provided with any conventional means for maintenance and control ofthe proper temperature conditions therein. As a mattel of catalysteconomy, the charge is with advantage preheated to the reactiontemperature prior to its introduction into the catalyst chamber. Heatexchange between the charge and materials flowing through other parts ofthe system may be utilized in suchpreheating as may expedient in anyparticular system. Conventional recovery and fractionation equipment maybe used to collect and separate the liquid hydrocarbon product ofgasoline boiling range.

The following example embodying specific operations in accordance withour. invention will illustrate the advantages offered by alkylation of ahydrocarbon mixture containing a substantial proportion of C5hydrocarbons as com pared with a product obtained from a similarcharging stock treated by the customary low pressure polymerizationoperation. The alkylation was effected by passing the charging stock 0through two catalyst towers in 'series, the temperature of the twotowers being 300 and 400 F.,- respectively, the gauge pressure-being 800lbs. per square inch in both towers, and thefeed rate'being 0.64 and0.96 gallon per hour per pound of catalyst in the first and secondtowers, respectively. The charging stock, comprising a debutanizerliquid overhead, for the alkylation and polymerization operations wasthe same and had the following composition:

Feed stock CH4 mol. percent .liq. percent. 0. 8 0.5 CZHI mol. percent.liq. percent. 0. 2 0. l 02H! mol. percent liq. percent 1. 6 1.3 O bitmol. percent liq. percent 11. 3 9.6 03H! mol. percent .liq. percent l6,1 14. 9 C4Hgmol. percent .liq. percent.. 25.8 23.7 0 H; mol. percent.liq percent. 22. 9 25. 0 0; mol. percent liq.perccnt.. 21.3 24.0

The products obtained by alkylation and by polymerization werestabilized to 06+ and had the following characteristics:

Alkyla Polymerition zation Gravity, API to" F.: as. 1 52.0 Initialpoint, "F 158 130 End point, F 467 512 Percent distilled at 392 F 93. 087. 0

The foregoing comparison demonstrates the improved results which may beobtained by alkylation of a hydrocarbon mixture containing a substantialportion of C5 hydrocarbons and shows the minimized tendency towardover-polymerization in the case of alkylation as compared withpolymerization. This minimized tendency toward overpolymerization islargely due to the low temperatures which may be used in the alkylationoflow boiling hydrocarbons. Furthermore, the low operating temperaturein the alkylation process prevents or at least minimizes local hightemperature zones on the surface of the catalyst because of the liquidphase operation resulting from the temperature and pressure conditionsemployed in the alkylation process. The presence of C5 hydrocarbons inthe charging stock aids in the maintenance of a liquid phase in'thecatalyst towers. The heat of polymerization is more rapidly dissipatedfrom the catalyst surface during alkylation than during polymerizationby vir-' tue of the fact that heat transfer is more emcient in a liquidmedium, occurringduring alkylation,

.than in a gaseous medium, occurring during polymerization. The coolingeffected by vaporization of liquid at the catalyst surface furthercondensation of the C5- hydrocarbons.

ture zones in the catalyst. The low temperature thus maintained in thecatalyst bed materially lengthens the life of the catalyst to a valueseveral times as great as the catalyst life for polymerizationprocesses.

The product obtained by alkylation of low boiling hydrocarbonscontaining a substantial amount of C5 hydrocarbons is furthercharacterized by higher yields, higher octane value and higher leadsusceptibility than a product obtained by polymerization of similarcharging stock. Thus a yield increase of 8.5% of gasoline, having a Reidvapor pressure of 9 lbs., is obtained by alkyla- .tion of a chargingstock comprising C5 hydrocarbons at 300-400 F. and 800 lbs. pressure ascompared to a 3.4% yield increase obtained by low pressurepolymerization of a charging stock comprising C4- hydrocarbons at380-500 F. and 160 lbs. pressure, these increases being measured as ayield of such gasoline over and above that obtained directly from acracking plant without crease of 0.5 in the octane number of the gaso-'line-like condensation product is produced by alkylating the 05'-hydrocarbons over the octane number of the product obtained bypolymerization of C4 hydrocarbons; This increase in the minimizes theformation of local high tempera-' An inoctane number of the gasoline isapparently 'due to the conversion of C5 hydrocarbons having an octaneblending value-of to into gasolinelike hydrocarbons having an octaneblending value of 90 to 100. By octane value we refer to the octanenumber determined by the Cooperative tuel research motor method. By

blending value we refer tothe apparent octane value of the product inblends with other gasolines of known lower octane value. The leadsusceptibility of the gasoline obtained by alkylation of C5-hydrocarbons is 8.6, whereas that obtained by polymerization of C4hydrocarbons is only 7.4. The gasoline from untreated distillates has astill lower lead susceptibility of 6.6. This higher lead susceptibilityobtained in accordance with our invention appears to be due to theproduction of more paraiiinic gasoline by alkylation and to the removalof unsaturated C5 hydrocar- Our invention makes possible the'recovery ofyields substantially larger than could be had from polymerization of.unsaturates to the substantial exclusion of alkylation. Ourinventionenables the recovery of yields deriving as much as 15% to 45% or morefrom saturates. Another advantage of our process resides in the factthat it makes available, for the production of liquid gasoline-likeproducts, hydrocarbon materials which hitherto either could not be soused at all or could not be so used economically. .Our process derivesspecial advantage from the fact that ethane and propane, particularly,are thus recoverable as liquid gasoline-like products.

Butane and pentane, for example, can be dehydrogenated and the resultingunsaturated products then catalytically polymerized, or they can bepolymerized by thermal processes involving fuels, to provide propervapor pressure characteristics, whereas ethane and propane are notuseful in this manner. In this aspect, our process provides for therecovery of a valuable liquid product from such saturated hydrocarbons,:thane and propane particularly, which hitherto have had little if anymore than fuel value.

To the extent that liquid phase conditions are maintained in the regionof catalyst contact, our process enjoys several further incidentaladvan- Jages. High capacities per unit of given size are thus attained.The catalyst is thus subjected to more or less continuous washing.Heavier condensation products which resist desorption in vapor phaseoperation and which tend to limit .he efiect of the catalyst as a matterof displacement are thus removed. Such washing, in conjunction with thelower temperatures used, also appears to prolong the useful life of thephosphoric acid catalyst.

We claim:

1. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which :omprises passing amixture of such hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial portion of C5 hydrocarbons incontact with a phosphoric acid' catalyst at a temperature of about200-450 F.

0 under a pressure upwards of about 500 lbs. per

square inch, whereby substantial condensation of saturates andunsaturates is effected.

2. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsatu- "ates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial amount of C5 Hydrocarbons,said mixture of hydrocarbons further containing not less than about 40mol percent. of ethane, propane and butanes and a substantial proportionbut not more than about mol percent. of normal butylene and isobutylenein its total content of C4- hydrocarbons, in contact with a phosphoricacid catalyst at a temperature of about 200-450 F. under a pressureupwards of about 500 lbs. per square inch, whereby substantialcondensation of saturates and unsaturates is effected.

3. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial proportion but not more thanabout 25 mol percent. of C5 hydroarbons on its total content of C5-hydrocarbons in contact with a phosphoric acid catalyst at a temperatureof about 200-45 0 F. under a pres sure upwards of about 500 lbs. persquare inch, whereby substantial condensation of saturates :ndunsaturates is effected.

4. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of(Er-hydrocarbons and containing a substantial proportion but not morethan about 25 molpercent. of C5 hydrocarbons on its total content of Chydrocarbons, said mixture of hydrocarbons further containing not lessthan about 40 mol percent. of ethane,

propane and butanes and a substantial proportion but not more than about25 mol percent. of normal butylene and isobutylene on its total contentof C4 hydrocarbons, in contact with a phosphoric acid catalyst at atemperature of about 20Q-450 F, under a pressure upwards of about 500lbs. per square inch, whereby substantial condensation of saturates andunsaturates is eifected. V

5. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial proportion of C5 hydrocarbons,said mixture of hydrocarbons further containing not less than about 40mol percent. of ethane, propane and butanes, not less than about 15 molpercent. of ethane and propane and a substantial proportion but not morethan about 25 mol percent. of normal butylene and isobutylene on itstotal content of C4- hydrocarbons,in contact with a phosphoric acidcatalyst at a temperature of about 200-450 F. under a pressure upwardsof about 500 lbs. per square inch, whereby substantial condensation ofsaturates and unsaturates is efiected.

6. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial proportion of C5 hydrocarbons,said mixture of hydrocarbons further containing not less than about 40mol percent. of ethane, propane and butanes and a substantial proportionbutnot more than about 40 mol percent. of ethylene, propylene andbutylenes on its total content of C4- hydrocarbons, in. contact with aphosphoric acid catalyst at a temperature of about 200-450 F. under apressure upwards of about 500 lbs. per square'inch, whereby substantialcondensation of saturates and unsaturates is effected.

7. In the catalytic condensation of low boiling gasolineboilingrange,'the improvement which comprises passing a mixture of suchhydrocarbons consisting predominantly of C4- hydrocarbons and containinga substantial proportion of C5 hydrocarbons, said mixture ofhydrocarbons further containing not less than about 40 mol percent. ofethane, propane, and butanes, not less than about 15 mol percent. ofethane and propane, a substantial proportion but not more than about 35mol percent. of ethylene. propylene and butylenes, and not more thanabout 25 mol percent, of normal butylene and isobutylene on its totalcontent of C4- hydrocarbons, in contact with a phosphoric acid catalystat a temperature of about 200-450 F. under a pressure upwards of about500 lbs. per square inch, whereby substantial condensation of saturatesand unsaturates is eflected. I

8. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of C4 hydrocarbonsand containing a substantial portion of C5 hydrocarbons incontact with aphosphoric acid catalyst at a temperature of about 200-360 F. under apressure upwards of about .700 lbs. per square inch, whereby substantialcondensation of saturates and unsaturates is efiected.

9. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial amount of C5 hydrocarbons,said mixture of hydrocarbons further containing not less than about 40mol per-- cent. of ethane, propane and butanes and a substantialproportion but not more than about mol percent. of normal butylene andisobutylene on its total content of C4- hydrocarbons, in con- 3 tactwith a phosphoric acid catalyst at a temper- 10. In the catalyticcondensation of low boiling hydrocarbons including saturates andunsatu'rates to produce normally liquid hydrocarbons of gasoline boilingrange, the improvement which comprises passing a mixture or suchhydrocarbons consisting predominantly of C4- hydrocarbons and containinga substantial proportion but not more than about 25 mol percent. of C5hydro-' carbons on its total content of C5- hydrocarbons in contactwitha phosphoric acid catalyst at a temperature of about 200-360 F. under apressure upwards of about 700 lbsaper square inch; whereby substantialcondensation of saturates and unsaturates is effected.

11. In the catalytic condensation of low boiling hydrocarbons includingsaturates and unsaturates to produce normally liquid hydrocarbons ofgasoline boiling range, the improvement which comprises passing amixture of such 'hydrocarbons consisting predominantly of C4-hydrocarbons and containing a substantial proportion but not more thanabout 25 mol percent. of C5 hydroe carbons on its total content ofCahydrocarbons said mixture of hydrocarbons further containing not lessthan about 40 mol percent. of ethane, propane and butanes and asubstantial proportion but not more than about 25 mol per cent. of

normal butylene and isobutylene on its total con- RODERICK n. pmmi. wnmumnmms.

